Method of molding articles from pulp material



Sept. 24, 1935 A. c. GOUG H METHOD OF MOLDING ARTICLES FROM PULP MATERIAL Original Filed March 5, 1953 ATTORNEY Patented Sept. 24, 1935 UNITED STATES PATENT OFFICE METHOD OF MOLDING ARTICLES FROM PULP MATERIAL Arthur C. Gough, Fitchburg, Mass, assignor to Charles F. Cowdrey, Jr., Fitchburg, Mass.

4 Claims. (Cl. 1859) This invention relates to a method of molding articles from pulp material and is a division of an application filed by applicant Ser. No. 659,470, filed March 3, 1933.

The obj ect of the present invention is to provide a method whereby composite articles may be formed of pulp material and a metallic ring be secured in the pulp material at a convenient location. Generally stated the method of the present "invention consists of forming an inner and an are in a moist or plastic condition, then subjecting the assembly to pressure which serves to unite the two members and cause the metallic ring to be embedded in the pulp material.

The method will be hereinafter described in connection with the formation of closures or bottle caps, but it is understood that the invention has a wider adaptation as'pointed out by the claims. r v 7 It has long been recognized'that closures for containers, especially where the container or bottle is intended for the distribution of milk, shall not only effectively seal the mouth of the bottle or container, but that due regard must be had for the prevention of contamination of the milk or other liquid by foreign substances.

Much study and ingenuity have been exercised in procuring a proper seal for a container, such as milk bottles, and one of the developments has proposed the formation of a cap of paper or the like with a depressed central portion forming a disk-like closure with the side portions of the cap extending over the top of the bottle and secured in place by a non-resilient metallic member which has been contracted about the bottle or container below its upper surface. In such case, however, an accumulation of foreign material upon a depressed portion of the cap renders this character of cap or closure objectionable.

With the above generally stated conditions in mind, the method of the present invention aims to provide a closure or bottle cap or similar article in which the sealing characteristic of the closure or cap is more effectively secured by a molding operation in which the cap is formed of two members which present in the completed cap a topfiush surface, a sealing rib extending into the bottle and a metallic ring embedded in the pulp material during the formation of the cap.

The method and the characterizing features thereof will be hereinafter described in connection with the accompanying drawing, which shows a bottle cap formed in accordance with the invention.

In the drawing:

Fig. 1 represents in perspective and in separated relation the two members of the cap or closure with a sealing ring ready to be applied between said members, some of the parts being broken away for clearness of illustration;

Fig. 2 is a section through the cap or closure showing the inner and outer members thereof as- 10 sembled with the non-resilient metallic ring embedded in the pulp material;

Fig. 3 represents in section the next step of making the cap or closure and wherein the downwardly extending bulge has been reversely turned and partially completed;

Fig. 4 shows the final step in the method wherein the downwardly extending bulge has been subjccted to a closing pressure to form a plain disklike top to the cap or closure and a sealing rib extending downwardly from the under side of the disk-like top;

Fig. 5 is asection through the top portion of a milk bottle showing the cap or closure assembled therewith ready to have the skirts of the cap contracted about the bottle or container below the mouth thereof; V

Fig. 6 is a perspective View showing a top portion of a milk bottle having the finished cap or closure applied and contracted about the neck of the container or bottle;

Fig. 7 is an enlarged perspective broken away showing more particularly the non-resilient metallic ring positioned in the pulp material of the bottle cap skirts; and

Fig. 8 is a sectional view of a modified form of a milk bottle with the cap of the present invention applied.

In the formation of the closure or bottle cap in accordance with the present invention both the 40 inner and outer members are formed of pulp material so that when the two members are assembled under pressure the non-resilient metallic ring placed between the .two members will be forced into the pulp material of said members while they are in a moist or plastic condition.

In Fig. l the outer member I is represented as formed of pulp material having the depending skirt '2 formed with an outwardly extending shoulder 3 a substantial distance above the lower edge of the skirt.

Central of the skirt 2 the outer member is provided with'a downwardly extending bulge 4 which is produced during the molding operation under suitable dies or the like. The inner member 5 of seats upon the outwardly extending shoulder 8 Y which thus acts as a positioning element for positioning the non-resilient metallic ring in proper relation to the skirt or skirts of the inner and outer members. Were it not for the positioning shoulder 8 the metallic ring 9 would be liable to take an inclined position withrespect to the skirt of the inner member 5 whereas with the outwardly extending shoulder B the metallic ring 9 is accurately seated in proper position' upon the skirt ofone of the members, so that when the members are assembled, as represented in Fig. 2, the metallic ring 9 is accurately positioned a uniform distance from and a substantial distance above the lower edge of the skirt.

The inner and outer members I and 5 having been assembled as presented in Fig. 2 with a non-resilient metallic ring 9 seated upon the shoulders of one of the members while those members are still in a moist or plastic condition, the assembling pressure is applied to cause the still moist or plastic inner and outer members of the cap to become cemented together and the non-resilient metallic ring 9 to be embedded into the pulp material of the two skirts so that the non-resilient metallic ring becomes fixed in the pulp material between the two skirts.

As hereinbefore suggested, one of the features of the present invention is the formation of a sealing rib projecting downwardlly from the under surface of the disk-like top of the finished cap or closure and in the operation following that of Fig. 2, the two bulges 4 and 1 of the outer and inner members of the cap or closure are subjected to an upward or reverse pressure to carry the lower wall In of the bulge of both members in an upward direction or into the position more clearly indicated in Fig. 3, it being understood that at this time the inner and outer members formed of wet or moist pulp material and cemented together bypressure with the nonresilient metallic ring 9 accurately positioned in the pulp material of the skirts, will have the lower walls of the bulges 4 and I forced into a plane at the top of the cap or closure.

Insomuch as it is one of the objects of the present invention to provide a plain disk-like top to the cap or closure with a downwardly extending sealing rib, the walls of the sealing rib or closure are forced towards each other by pressure so that the sealing rib l l takes the form represented in Fig. 4, thereby closing the opening at the top of the cap or closure to prevent any foreign substance from lodging therein.

The completed cap or closure is represented in Fig. 4, wherein it will be noted that the nonresilient metallic ring 9 is embedded in the wet or moist pulp material of the skirts of the inner and outer members and that the cap or closure presents a disk-like top with no depression or space for the reception of foreign substances and from the lower surface of the disklike top the flexible sealing rib ll extends downwardly so that its exterior circumferential surbottle mouth, it is appropriate to form at; least 10 one of the walls of the sealing rib II on a slight incline a b which converges downwardly, as indicated in Fig. 4, with the result that where the bottle mouths vary slightly in their contour or size, the sealing rib will, nevertheless, seal with 15 tight pressure against the adjacent vertical wall of the bottle mouth and be held there in sealing position when the skirts of the cap and the nonresilient metallic ring 9 are contracted about the neck of the bottle, as indicated in Fig, 6.

Fig. 8 indicates a modified bottle top in section from which has been omitted the usual shoulder [3 now present in most milk bottles, but since the sealing rib ll yieldingly seals or bears against the interior vertical surface of the 25 bottle mouth the omission of the shoulder I3 has no effect in the complete and effective sealing of the rib I l in its sealing function.

It is a commonly observable condition that when the milk freezes in a bottle it expands up- 30 wardly because this is the only direction it may go and in the bottle caps of the prior art so far as is known to applicant, the effect is that the cap or closure will either be broken or detached from the bottle entirely. In applicants case, 85 however, since the sealing rib H is formed by reverse bends in the inner and outer members of the cap or closure, it offers a give way construction which, when the milk freeezs will cause the disk-like top of the cap or closure to rise by the unfolding of the sealing rib II, with the result that even though the milk-becomes frozenin the bottle it remains effectively sealed by the downwardly extending skirts and non-resilient metallic ring against the exterior below the bottle 4 mouth.

Where the non-resilient metallic ring is embedded in the pulp material of the skirts of the inner and outer members, as hereinbefore described, it becomes a permanent part of the bottle 50 cap or closure and offers no projecting portion for the collection of foreign substances.

The cap or closure having been placed upon the bottle and the skirts folded inwardly with the non-resilient metallic ring, as represented in Fig. 55 6, it offers facile condition for the house-wife to remove the cap readily by opening outwardly one or more of the folds or pleats along with the non-resilient metallic ring to thereby remove the cap from the bottle or container and then replace 6 it if desirable and turn the pleats or folds of the skirt inwardly again to hold the cap temporarily in place.

Following the completion of the cap or closure, as shown in Fig. 4, it is dried, or it may be subjected to a heat treatment to set the portion of the cap or closure which, however, still retains flexibility in the skirts to permit being contracted about the container below the mouth thereof.

What is claimed is:-

1. The method of forming articles of wet pulp material, which consists in molding two members from wet or moist pulp material, each with a skirt and forming a ring positioning shoulder on the skirts, then placing a metallic ring on the shoulder of one of the skirts, assembling the two members one within the other, and subjecting the assembled members to pressure while in a moist or plastic condition to force the metal ring bodily into the substance of the pulp material of both of the two skirts.-

2. The method of forming a closure for containers, which consists in molding an inner and. an outer member from wet pulp material, each with a depending skirt and a central bulge extending inwardly from the top within the confines of the skirt, then assembling the two members in superposed relation under pressure while in a moist or plastic condition, and subjecting the central bulge of the assembled members to a reverse bulge bending pressure to form a disk-like top for the closure and a depending sealing rib extending inwardly from the disk-like top.

3. The method of forming a closure for containers, which consists in molding an inner and an outer member from wet or moist pulp material, each with a depending skirt and a central bulge extending from the top within the confines of the skirt, placing a metallic ring on the skirt of one of said members, then assembling the two members under pressure while in a moist or plastic condition to cause the metallic ring to be bodily incorporated in the pulp material of the skirts and unite the two members, and subjecting the bulges of the assembled members to a reverse bulge bending pressure to form a disk-like top for the closure and a sealing rib extending inwardly from the disk-like top.

4. The method of making a closure for containers which consists in molding cup shaped outer member and a similar cup shaped inner member each with a depending skirt, forming a,

central bulge on each of said members extending within the confines of their respective skirts, assembling the two members in superposed relation, then subjecting the assembled inner and outer members to pressure to unite the two while the pulp material is in a wet or moist condition, and 20 

